Questions & Answers about Zašto oni uvijek šute?
The verb here is šute. What is the infinitive, and how do we get this form?
The infinitive is šutjeti (to be silent). This belongs to the group of regular -jeti verbs. To make the "they" form (third-person plural) for these verbs, you take the base of the word and add the ending -e, which gives us šute.
Is it strictly necessary to include the pronoun oni (they) in this sentence?
No, you could just ask Zašto uvijek šute? Croatian often drops subject pronouns because the verb ending (like the -e in šute) already tells us exactly who is doing the action. Including oni here just adds a little bit of emphasis or makes the subject completely clear.
Can I put the word uvijek at the end of the sentence instead?
You could say Zašto oni šute uvijek?, but putting uvijek (always) right before the verb sounds much more natural. In Croatian, short adverbs of time usually go just before the verb they are describing.
Does šute have a rude meaning, similar to "shut up" in English?
No, even though the words sound a bit similar, šutjeti is a perfectly neutral and polite verb. It simply means to be silent or to keep quiet, without any of the rudeness of the English phrase "shut up".